Mobility Control by Polymers Under Bottom-Water Conditions, Experimental Approach

Mobility Control by Polymers Under Bottom-Water Conditions, Experimental Approach Ezeddin Shirif Ezeddin Shirif University of Regina Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Asia Pacific Oil and Gas Conference and Exhibition, Brisbane, Australia, October 2000. Paper Number: SPE-64506-MS https://doi.org/10.2118/64506-MS Published: October 16 2000 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Shirif, Ezeddin. "Mobility Control by Polymers Under Bottom-Water Conditions, Experimental Approach." Paper presented at the SPE Asia Pacific Oil and Gas Conference and Exhibition, Brisbane, Australia, October 2000. doi: https://doi.org/10.2118/64506-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Asia Pacific Oil and Gas Conference and Exhibition Search Advanced Search AbstractIn many light or moderately viscous oil reservoirs in Saskatchewan and Alberta, a high water saturation zone ovarying thickness and extent ("bottom-water zone") occurs in communication with the oil zone above. As a result, the primary production period is short, and water coning occurs very early in the life of the reservoir. Later, during the secondary recovery stage, such a zone can have an adverse effect on the waterflood efficiency. This research addresses the problem of waterflooding such reservoirs.This study was directed towards reducing water mobility in the bottom-water zone for more efficient oil displacement. Polymer in various concentrations was used as a blocking agent in the bottom-water zone and as a mobility control agent in the oil zone. Different strategies were investigated to reduce the water mobility in the bottom-water zone and improve the vertical sweep efficiency. The variables examined were: relative water-oil layer thickness, oil viscosity, polymer concentration, injection rate and injection point, as well as the effect of vertical and horizontal injection and production wells.The results showed that oil recovery could be increased by minimizing crossflow between layers by blocking the bottom-water zone completely. It was also found that for an unfavourable mobility ratio, as the injection rate increases the ultimate oil recovery increases. The injection of a polymer solution had a favourable impact on waterflood performance. Moreover, the worse the conventional waterflood performance was, the more effective the polymer was as a mobility and blocking control agent. The use of horizontal wells showed slightly better oil recovery over vertical wells in a conventional waterflood of reservoirs under bottom-water conditions. In addition, some certain well combinations (horizontal production and vertical injection) gave better oil recovery due to the increase in the swept area.IntroductionThe efficient and economic recovery of oil from reservoirs under bottom-water conditions is recognized as a formidable task. High water cuts and rapidly decreasing oil rates early in the production life of such reservoirs have in many instances prompted their suspension or abandonment at very low levels of oil recovery. Reservoir characteristics and rock and fluid properties combine to yield the single most important parameter (mobility ratio) in a waterflood. A number of chemicals such as polymers, emulsion, biopolymer, foam and carbon dioxide-activated silica gel have been used to control the mobility ratio.One of the oldest techniques to control mobility of water in waterflooding is the use of polymers. This control agent was shown to be effective in the early sixties by Pye1. He performed numerous field and laboratory studies of polymer flooding using polyacrylamide solutions. It was observed experimentally that the viscosity of the water-soluble polymer solutions measured in the formation sample departed markedly from that obtained using a viscometer. He quantified the unusual departure of the measured values from the expected response as the resistance factor. It was assumed that the permeability was constant.Pye pointed out that at constant flow the injection pressure rose, and this effect was not a core plugging problem because the system reached equilibrium after some time. It was also observed that the extent of departure from the measured viscosity value was most pronounced at low concentrations but at higher concentrations the effect was approximately proportional to the solution viscosity. It was suggested that this unusual behaviour was a property of only selected water-soluble polymers, among which were the extensive family of acrylamide polymers and copolymers. It was recommended that rapid laboratory flood rates should be avoided in order to keep the resistance factor constant. Keywords: bottom-water zone, ezeddin shirif spe 64506, injection, spe 64506, permeability, polymer, concentration, bottom-water condition, upstream oil & gas, oil recovery Subjects: Improved and Enhanced Recovery, Waterflooding This content is only available via PDF. 2000. Society of Petroleum Engineers You can access this article if you purchase or spend a download.

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